One of the basic StackExchange rules is that soliciting product recommendations is verboten. Hence Graphical diff for Mac OS X, which turned up when I searched the Web (not SO) for OSX graphical diff tools, was closed as Not Constructive with 300+ upvotes for the question, 300+ upvotes for the selected answer, 87 votes for the runner-up...
This sounds to me like "SO rules know better than the community what the community needs." This is really a lot of upvotes for a nonstarter category of question.
Is there someplace within the StackExchange framework where this kind of questions may be asked? xyz.recommendations.stackexchange.com? As pointed out in the comments, having a graphical diff tool is a real programming need and it can be within the interests of programmers to have tool needs addressed. Now it may be that this is formally classified as Not Constructive, but this is a juridical decision that should be able to be vetoed by overwhelming upvotes.
Perhaps n (50 or so) upvotes could say, "This justifies an exception", and be seen as a veto to a juridical classification of "Not Constructive" (just very helpful to hundreds of StackOverflow visitors).